This invention relates in general to support mats for supporting heavy equipment, and in particular, to an improved support mat and a method of making such support mats.
The construction industry utilizes solid sawn wood and wood panel members in a variety of forms to aid in the erection of buildings, roads, and bridges. For example, temporary road panels and crane mats are often constructed using solid-sawn hardwood timbers or some species of softwoods. These panels are used to form a temporary lightweight roadway or foundation to facilitate vehicular and equipment travel as may be required in construction operations. Other industry users of such mats include users in the field of pipeline, utility, transportation, oil, and infrastructure.
As shown in FIG. 1, a conventional road panel, shown generally at 10, is formed by using a plurality of solid sawn timber elements 12. Typically, four pieces of solid sawn timber 12 are used, each having a cross-sectional dimension ranging from about 8 inches×8 inches to about 12 inches×12 inches, with a length of 16 feet. The four pieces of timber 12 are usually bolted together using bolts 14 to form the temporary road panel 10 having an assembled dimension of 4 feet×1 foot×16 feet. Several panels can be placed side by side over existing ground to form a temporary roadway or to support cranes on a construction site. Ground conditions under the panels vary greatly and may include, for example, sand, clay, wetlands, and possibly a considerable amount of water. Another conventional wood mat utilizes smaller dimensional lumber and utilizes nails, carriage bolts, or steel rods as a fastening system. All of these systems have mechanical fastening systems to transfer stresses between components.
The hardwood panels are typically discarded at the end of the construction project, or they may be re-used if they are in relatively good condition. The longevity of the panels may be as little as six months to one year, depending on the length of the construction project and the environmental conditions to which the panels are subjected. The wood panels are typically untreated with preservative chemicals because of environmental concerns. Hardwoods are typically used because of their superior wear resistance to heavy truck and other construction equipment traffic. In addition to road panels and crane mats, other applications for the hardwood panels include decks over steel girders for temporary bridges, and soldier piles.
Because the timber used to form the panel 10 is expensive, the panel 10 is very costly. Further, the roadway formed by the panels 10 is very costly because tens of thousands of the panels 10 may be used for a single construction project. In addition, the solid sawn timber used to form the panel 10 is scarce because of the solid sawn timber must be extremely long, typically about sixteen feet in length. Further, each timber 12 is typically has an allowable design strength value within the range of from about 650 psi (pounds per square inch) to about 700 psi., thereby limiting the type and size of equipment which can be supported thereon. Therefore, it would be desirable to provide an improved support mat for supporting heavy equipment.